DNS 1 FORMERR vs 21 BADALG
Both DNS 1 (FORMERR) and 21 (BADALG) belong to the DNS Response Codes (RCODEs) category. 1 indicates that format error. The name server was unable to interpret the query due to a malformed DNS message. Meanwhile, 21 means that algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Descripción
Format error. The name server was unable to interpret the query due to a malformed DNS message.
Cuándo lo verás
Your DNS client or library sent a query the server could not parse, often caused by a buggy resolver, corrupted packet, or unsupported EDNS options.
Cómo solucionarlo
Check your DNS client or library version for known bugs. Capture the raw query with dig or Wireshark and verify it conforms to the DNS wire format.
Descripción
Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Cuándo lo verás
Your TKEY negotiation or DNSSEC operation requested an algorithm (e.g., HMAC-SHA512) that the server has not been compiled with or configured to accept.
Cómo solucionarlo
Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.
Diferencias clave
DNS 1: Format error. The name server was unable to interpret the query due to a malformed DNS message.
DNS 21: Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
You encounter 1 when your DNS client or library sent a query the server could not parse, often caused by a buggy resolver, corrupted packet, or unsupported EDNS options.
You encounter 21 when your TKEY negotiation or DNSSEC operation requested an algorithm (e.g., HMAC-SHA512) that the server has not been compiled with or configured to accept.
Cuándo usar cada uno
For 1 (FORMERR): Check your DNS client or library version for known bugs. Capture the raw query with dig or Wireshark and verify it conforms to the DNS wire format. For 21 (BADALG): Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.